Patent Application
20240384648
This disclosure relates to releasing tracers within wellbores, e.g., to analyze properties of hydrocarbon flow through the wellbores.
During hydrocarbon production, a single wellbore can produce from multiple production zones by passing through multiple, stacked production zones, branching out into sidetrack wellbores, or through other arrangements. In some implementations, production fluid from various production zones are directed through the wellbore by separate production tubing. In some implementations, the production fluid from various production zones are comingled and directed through a single production tubing string. Once at a topside facility, the production fluid is separated into its various components: oil, water, and gas.
This specification describes technologies relating to controlled release of tracers into multi-lateral wells.
Certain aspects of the subject matter described here can be implemented as a method in a wellbore formed in a subterranean zone from a surface of the Earth. A lateral is formed from the wellbore into the subterranean zone. Hydrocarbons entrapped in the subterranean zone flow into the lateral. A wellbore production tubing is installed within the wellbore and extend toward the lateral. The wellbore production tubing defines an annulus between an outer surface of the wellbore production tubing and an inner wall of the wellbore. A portion of the hydrocarbons flowing from the lateral into the annulus flow within an internal volume defined by a body attached to the outer surface of the wellbore production tubing. The portion of the hydrocarbons mix with tracers residing within the internal volume. A mixture of the portion of the hydrocarbons with a portion of the tracers flow out of the internal volume and towards the surface. At the surface, a concentration of the tracers in the mixture flowed to the surface is analyzed. Based on a result of the analyzing, properties of hydrocarbon flow into the lateral are determined.
An aspect combinable with any other aspect includes the following features. To flow the portion of the hydrocarbons within the internal volume defined by the body, the body is attached to the outer surface of the wellbore production tubing at a downhole location that is downstream of an inlet to the lateral.
An aspect combinable with any other aspect includes the following features. The body includes an inlet to the internal volume that is downstream of the inlet to the lateral and an outlet from the internal volume that is downstream of the inlet of the body. To flow the portion of the hydrocarbons within the internal volume, the portion of the hydrocarbons are flowed into the inlet of the body.
An aspect combinable with any other aspect includes the following features. The tracers are flowed into the internal volume before flowing the portion of the hydrocarbons into the inlet of the body.
An aspect combinable with any other aspect includes the following features. The tracers are flowed from a reservoir at the surface through a flowline that extends from the surface to within the internal volume of the body.
An aspect combinable with any other aspect includes the following features. To analyze the concentration of the tracers in the mixture flowed to the surface, after flowing the mixture into the wellbore production tubing, flow of the tracers into the internal volume is shut off. Then, a time rate of decay of the concentration of the tracers reaching the surface of the wellbore is measured.
An aspect combinable with any other aspect includes the following features. A check valve is fluidically disposed in the flowline. The check valve is configured to permit flow of the tracers within the internal volume through the flowline and to prevent flow out of the internal volume through the flowline.
An aspect combinable with any other aspect includes the following features. To flow the mixture into the wellbore production tubing and towards the surface, an inflow control valve to flow the mixture from the annulus into the wellbore production tubing is operated.
An aspect combinable with any other aspect includes the following features. To flow, out of the internal volume and towards the surface, the mixture of the portion of the hydrocarbons with a portion of the tracers, a duration for which the portion of the hydrocarbons resides within the internal volume is increased before flowing the mixture out of the internal volume.
An aspect combinable with any other aspect includes the following features. To increase the duration, the internal volume is filled with porous beads between the inlet and the outlet.
An aspect combinable with any other aspect includes the following features. To increase the duration, multiple baffles are positioned within the internal volume between the inlet and the outlet.
Certain aspects of the subject matter described here can be implemented as an apparatus. The apparatus includes a body defining an internal volume. The body can be attached to an outer surface of a wellbore production tubing in an annulus defined by the outer surface of the wellbore production tubing and an inner wall of a wellbore formed in a subterranean zone from a surface of the Earth. A lateral is formed in the subterranean zone. Hydrocarbons entrapped in the subterranean zone flow into the lateral, into the annulus and towards the surface. The body includes an inlet to and outlet from the internal volume; each defined on a surface of the body. When the body is attached to the outer surface of the wellbore production tubing with the inlet nearer to the lateral than the outlet, the inlet allows at least a portion of the hydrocarbons to enter the internal volume and the outlet allows at least the portion of the hydrocarbons to exit the internal volume. A dosing line extends from the surface to within the internal volume. The dosing line is configured to flow fluid from the surface to the body. A tracer is configured to be flowed into the internal volume from the surface through the dosing line. At least a portion of the tracer is configured to mingle with at least the portion of the hydrocarbons that enter the internal volume through the inlet and to flow out of the body and to the surface with at least the portion of the hydrocarbons that exit through the outlet. A concentration of at least the portion of the tracer at the surface is indicative of a percentage of a total hydrocarbon flow coming into the lateral from the subterranean zone.
An aspect combinable with any other aspect includes the following features. The body includes multiple beads positioned within the internal volume. The multiple beads form a porous bed of beads between the inlet and the outlet. The tracer is distributed across the porous bed of beads.
An aspect combinable with any other aspect includes the following features. The body includes multiple baffles formed within the internal volume. A first end of each baffle is attached to an inner surface of the body. A second end of each baffle extends away from the inner surface into the internal volume. The multiple baffles define a tortuous flow path between the inlet and the outlet.
An aspect combinable with any other aspect includes the following features. The body defines a ring shape with a hollow center. The ring-shaped body is configured to be wrapped around the wellbore production tubing.
An aspect combinable with any other aspect includes the following features. A strap is configured to attach the body to the outer surface of the wellbore production tubing.
An aspect combinable with any other aspect includes the following features. The apparatus includes a check valve fluidically coupled to the dosing line. The check valve is configured to permit fluid flow from the surface into the body and to prevent fluid flow out of the body.
The details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.
Like reference numbers and designations in the various drawings indicate like elements.
To determine oil production rates and water cuts within multi-zone, comingled wells, tracers are injected into multiple zones. Each zone of tracers is barcoded to identify the zone. The tracers include hydrophilic and oleophilic tracers. A transient is performed on the tracer injection. The transient creates a decay profile that can be detected at the topside facility. The profiles for each individual production zone can be used to determine a water cut for each zone. The various production zones can then be throttled to optimize hydrocarbon production.
In some applications, tracers are used to analyze zonal flow contributions from multiple zones through which a well that has two (or more) lateral sections is formed. The zones are isolated from each other with packers. The flow from each lateral enters the motherbore (i.e., the common wellbore production tubing) through respective inflow control valves (ICVs). An ICV has a variable orifice dimension settable from the surface, e.g., via a hydraulic control line or via electrical control. Using the ICV, an operator can increase or throttle back flow from each lateral well independently. Such zonal flow control can be performed, e.g., to delay the onset and increase of total water production from the well.
In such applications, tracers are injected into separate annular spaces in the wellbore via respective dosing lines, i.e., tubulars or pipelines that run from a tracer reservoir at the surface to respective downhole locations in which tracers are to be deposited. Tracers injected into a zone are carried to the surface by well fluids (i.e., hydrocarbons) that flow into the zone through the lateral formed in the zone. The tracers can be oleophilic tags that can be used to identify oil production or hydrophilic tags that can be used to identify water production or a combination of the two. By measuring a concentration and other flow properties (e.g., volumetric flow rate) of the tracers at the surface, the oil production contributions of different laterals as well as water contributions can be determined. In particular, the oil production contributions can be analyzed only using surface measurements instead of downhole measurements using equipment such as cabling and electronics.
The transient method of quantifying flow rate contributions from multiple laterals using tracers employs an abrupt shut-off of the tracer injection and posits that the decay rate of tracer concentration following the shut-off is proportional to the flow contributed by the lateral in which the tracers were injected. In real-world production conditions, however, the flow rate can be high enough to result in decay times as short as a few seconds. Such rapid decay times create technical challenges for accurately capturing the decay rate. This disclosure describes techniques to slow the rate at which tracers are flushed out of the annular space while preserving the flow-rate dependent nature of the delay.
This disclosure describes a diffuser-like apparatus that can slow down the release of injected tracers while retaining a flow-dependent decay characteristic. Doing so enables measurements of zonal flow contributions over a wide range of flow rates. The apparatus disclosed here can be charged (i.e., filled or injected) with tracer from the surface using a dosing line at any time according to the needs of the operator, and can therefore be re-used indefinitely. The apparatus described here is passive and does not require batteries or any other power source. Consequently, the lifetime of the device is not limited by the apparatus' capacity to store tracers or the life of any batteries to operate the apparatus. Some implementations of the device contain no moving parts.
Tracers mixed with the isolated hydrocarbons flowing from the lateral 108 can be permitted to flow into the tubing 110 by the ICV 114. The tracers (schematically represented by circles 118 within the apparatus 102) can be stored in an internal volume defined by the apparatus 102. The apparatus 102 defines an inlet 120 through which a portion of the hydrocarbons from the lateral 108 enter the apparatus 102. Within the apparatus 102, the hydrocarbons mix with the tracers 118. The apparatus 102 defines an outlet 122 through which a mixture of the hydrocarbons and tracers exits the apparatus 102. In some implementations, the apparatus 102 is attached to the tubing 110 uphole of (i.e., downstream of) the lateral 108 such that the inlet 120 to the apparatus 102 is uphole of (i.e., downstream of) the lateral 108 and the outlet 122 to the apparatus is uphole of (i.e., downstream of) the inlet 120. The ICV 114, which permits the mixture of the tracers and hydrocarbons to enter the tubing 110, is uphole of (i.e., downstream of) the outlet 122.
In some implementations, the apparatus 102 includes a dosing line 124 (e.g., a tube or pipe) that extends from a surface of the wellbore 100 to within the internal volume 119 defined by the apparatus 102. At the surface, the dosing line 124 is connected to a reservoir and other flow equipment (not shown) using which tracers can be flowed through the dosing line 124 into the apparatus 102. Using the dosing line 124, an operator can fill (or refill) the apparatus 102 with tracers 118 so that a requisite volume of tracers 118 remains available at all times.
In an example operation, the apparatus 102 can be installed around the wellbore production tubing 110 before the tubing 110 is installed within the wellbore 100. The dosing line 124 is passed through the packer 116 with one end of the dosing line 124 extending into the internal volume 119 defined by the body of the apparatus 102 and the other end of the dosing line 124 extending to a reservoir and flow equipment at the surface. The internal volume 119 can be filled with tracers 118 before or after lowering the apparatus 102 into the wellbore 100.
Hydrocarbons flowing from the subterranean zone 104 into the lateral 108 enter the wellbore 100 and flow towards the surface. A portion of the hydrocarbons flow into the inlet 120 of the apparatus 102 and enter the internal volume 119. In the internal volume 119, the hydrocarbons mix with the tracers 118 in the internal volume 119. A pressure of the flow carries facilitates mixing of the hydrocarbons and the tracers 118, and also causes the mixture to flow towards the outlet 122 of the apparatus 122 and into the annulus. The ICV 114 is opened to permit the mixture of the tracers and the hydrocarbons to enter the tubing 110. To perform transient testing, after a quantity of the mixture of the hydrocarbons and tracers 118 enters the tubing 110, the ICV 114 is left open and an injection of the tracers is stopped. Then, a decay rate of the tracers 118 at the surface is analyzed at the surface (not downhole). By determining a concentration of the tracers 118 after the tracer injection has been stopped, properties of the hydrocarbon flow from the subterranean zone can be determined. Examples of properties that can be determined include a percentage of the total flow coming from the zone.
An operational efficiency of the apparatuses described in this disclosure depends, in part, on a quantity of tracers carried by the hydrocarbons to the surface. The quantity of tracers, in turn, depends on a time for which the hydrocarbons reside within the internal volume of the apparatus (residence time). One technique to control the residence time is to control a size of the openings (i.e., the inlet and the outlet) into the apparatus. Another technique to control a quantity of tracers that are mixed with the hydrocarbons is to control a bulk flow rate of the hydrocarbons through the annulus towards the surface. Further techniques to control the residence time are described with reference to
At 604, the hydrocarbons flowed into the body of the apparatus 102 mix with tracers in the body. For example, the apparatus 102 is filled with tracers that are flowed into the internal volume from the surface through the dosing line 124. The hydrocarbons that enter the internal volume while flowing in an uphole direction towards the surface mix with the tracers that already reside within the internal volume.
At 606, a mixture of the hydrocarbons and the tracers is flowed into the annulus. For example, whereas the hydrocarbons entered the internal volume through the inlet 120, a mixture of the hydrocarbons and the tracer exits the internal volume through the outlet 122 downstream of the inlet 120. The mixture that exits the internal volume flows into the annulus 112.
At 608, the mixture is flowed from the annulus into the production tubing and to the surface. For example, the ICV 114 is opened to permit the mixture of the hydrocarbons and the tracers to enter the tubing 110 and to flow to the surface.
At 610, a concentration of the tracers in the mixture is analyzed at the surface. For example, after a portion of the mixture of the tracers and hydrocarbons has flowed to the surface, tracer injection is shut-off. Samples of the mixture are obtained at the surface at different times and analyzed to determine a decay rate of the tracers.
At 612, properties of hydrocarbon flow in the lateral are determined based on a result of the analysis that was performed at the surface. For example, using the type of tracers collected at the surface, a percentage of the total flow coming from the zone into the lateral 108 is determined.
In some implementations, the process 600 can be extended to a multi-lateral well in which each lateral is formed in a respective zone. Flow from each lateral into the motherbore is isolated using multiple packers. Different apparatuses are attached to the production tubing in each isolated zone upstream of respective laterals. Each apparatus can be filled with respective tracers that are distinguishable from each other. In some implementations, each apparatus can include mechanisms (e.g., porous beads or baffles to form a tortuous pathway) to increase residence times of hydrocarbons in the respective apparatuses. By collecting samples from the different zones at the surface and analyzing tracers in the samples, the contributions of the different zones to the hydrocarbon flow through the motherbore can be determined. In addition, by implementing the transient analysis techniques, decay rates of tracers from each zone can be determined to further determine properties of the hydrocarbon flow from the different zones.
Thus, particular implementations of the subject matter have been described. Other implementations are within the scope of the following claims.
